| brain basher(noun, difficult, issue, question, task) |
| twister(noun, difficult, issue, question, task) |
| perplexity(noun, conundrum, twister, stumper, brain-teaser) |
| brainteaser(noun, difficult, issue, question, task) |
| conundrum(noun, difficult, issue, question, puzzle) |
| puzzle(noun, verb, conundrum, twister, stumper) |
| chinese puzzle(noun, difficult, issue, question, task) |
| eye teaser(noun, difficult, issue, question, task) |
| head-scratcher(noun, difficult, issue, question, task) |
| mind-teaser(noun, difficult, issue, question, task) |
| mindbender(noun, difficult, issue, question, task) |
| brain(noun, see, think, decide) |
| head(noun, see, think, decide) |
| mind(noun, see, think, decide) |
| mindgames(noun, difficult, issue, question, task) |
| puzzler(noun, difficult, issue, question, task) |
| secret(noun, conundrum, twister, stumper, brain-teaser) |
| stumper(noun, difficult, issue, question, task) |
| teaser(noun, difficult, issue, question, task) |
| thought(noun, see, think, decide) |